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Elevator
.]] .]] Elevator (or lift) is a vertical transport vehicle that efficiently moves people or goods between floors of a building. They are generally powered by electric motors that either drive traction cables and counterweight systems, or pump hydraulic fluid to raise a cylindrical piston. History Primitive elevators dates back to ancient Rome, where Archimedes designed one supported by hemp ropes and powered by animals. By the 1800's, the technology had not greatly improved and the elevators that existed were notoriously dangerous. Due to the high risk, these elevators were reserved almost solely for moving objects, not people. Medieval records contained numerous drawings of hoists lifting people and supplies to isolated locations. Among the most famous is the hoist at the monastery of St. Barlaam in Greece. The monastery stood on a pinnacle approximately 61 meters (200 ft) above the ground. Its hoist, which employed a basket or cargo net, was the only means up or down. At an abbey on the French seacoast, a hoist was installed in 1203 that used a large tread wheel. A donkey supplied the lifting power. The load was raised by a rope wound on a large drum. Manpower supplied the lifting force in many early devices. By the 18th century, machine power was being applied to the development of the elevator. In 1743, a counterweighted personal elevator was commissioned by Louis XV in France for his personal chambers in Versailles. By 1833, a system using reciprocating rods raised and lowered miners in Germany’s Harz Mountains. A belt-driven, steam powered elevator called the teagle was installed in an English factory in 1835. The first hydraulic industrial elevator powered by water pressure appeared in 1846. As machinery and engineering improved, other powered lifting devices quickly followed. Broken rope safety invention by Otis In 1853, an inventor named Elisha Otis had designed a safety system that would catch a falling lift should its main support fail. He proudly demonstrated this breakthrough at the 1853 World’s Fair in New York’s Crystal Palace. Otis stood on the elevated platform high above the crowd then directed a burly assistant to sever the support cable with an axe. The platform dropped a few inches but the safety system quickly stopped the descent. A few years later when a state-of-the-art building was constructed to house the E.V. Haughwout chinaware emporium, the architects decided to include the very first Otis passenger elevator at a cost of $300. That same elevator still exists, though not in original condition. The first successful passenger elevator was installed on this day at 488 Broadway in New York City on March 23, 1857. In 1880, Werner-von Siemens invented the first electric elevator. Elevator drive systems Traction Main article: Traction elevators Elevator Motor Unit.jpg|A geared traction machine. darryl_departure_60_elevator.jpg|Bottom-drive Hitachi traction elevators at Changi Airport Terminal 3, Singapore. The motor room is located at the bottom floor, while the top floor only have reflector sheaves. M.R.L. traction Main article: Machine Room Less Elevator Hydraulic Main article: Hydraulic elevators Elevator control Main article: Elevator control system As passengers step on and off an elevator, the load constantly changes, making it difficult to keep the platform level with the floor. Otis solved this problem as far back as 1915 with a self-leveling device called Microdrive. First developed for lifts in naval vessels, Otis introduced it as a safety device in passenger elevators. It also saved time and improved the ride quality for passengers as the leveling operation was automatic. Older elevators before 1980's uses mechanical selectors that uses analog controls and many moving parts to determine the car’s position, requiring constant and often costly maintenance. Judging when to slow the cab was easy enough for an operator when speeds were between 91-121 meters (300-400 ft) per minute. But when speeds increased to over 213 meters (700 ft) per minute, this became too difficult. The logical step was to automate the control system. In 1924, Otis installed its first Signal Control System in the new Standard Oil Building in New York City. The system automatically controlled acceleration, speed between floors and deceleration as the car approached the landing. In 1937, the Peak Period Control was introduced to automatically schedule elevator service during high-demand periods. It helped reduce the waiting time on any given floor by coordinating the movement of the building’s elevators. Elevator algorithm Main article: Elevator algorithm Types of elevators Main article: Types of elevators Elevators have many types for passengers and freight. Elevator special modes *Anti-Crime Protection (ACP) *Emergency power operation (EPR) *Fire service mode (EFS) *Independent service (ISC) *Inspection service (INS) *Medical emergency/Code Blue service (EHS) *Sabbath service (SHO) Elevator equipments *Elevator fixtures *Elevator doors *More. External Links *The Secret Life of the Lift (Secret Life Of Machines Series 3 (1993) by Tim Hunkin) *The Secret Life of the Lift by Tim Hunkin *What is an elevator? (by Dover Corp.) *hkelev - Elevator structures **Relevant models *How do Elevators (lifts) work? *